Abstract: Microwave enhanced solid-state acid degradation of chitosan was studied in this paper,the effects of microwave radiation power and hydrochloric acid dosage on the molecular weight of degraded products were analyzed,and their structure was characterized by infrared spectrum and proton nuclear magnetic resonance. The results showed that the increase of microwave radiation power and hydrochloric acid dosage would lead to decreased molecular weight. Low molecular weight chitosan with weight average molecular weight less than 50000 could be obtained by irradiating the solid-state acidification material under microwave for 15 minutes,and the structure of sugar unit remained stable during the reaction. The production capacity of chitooligosaccharide could be increased more than 4 times in unit time by the combination of microwave enhanced solid-state acid degradation and enzyme degradation. In conclusion,this study provided an efficient preparation method of low molecular weight chitosan and chitooligosaccharides based on microwave enhanced solid-state acid degradation technology,which laid a foundation for their various applications.